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Phil Richerme | CERN | Switzerland

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Hello! I’m Phil, a grad student working at CERN, and I’m new to Quantum Diaries. In truth, I’m new to blogging as well; however, I love talking about physics, sharing my thoughts, and hopefully giving people something new to think about.

Now that I’ve introduced myself, I’d like to introduce the ATRAP experiment. ATRAP has been at CERN for over 20 years now, working on experiments with antihydrogen – the simplest atom made completely from antimatter (an antiproton nucleus orbited by a positron). The long-term goal has remained the same: trap large numbers of antihydrogen atoms, measure their energy levels, and compare to (matter) hydrogen. This would allow us to very precisely test the CPT theorem, which predicts identical agreement between the two. Any difference in the energy levels of hydrogen and antihydrogen would violate CPT (a fairly central theorem in physics), and could only be explained by new physics beyond the standard model.

We’re not the typical CERN experiment. For one, our collaboration has orders of magnitude fewer people than the big CERN groups (there were 17 co-authors on our last paper). Also, unlike most CERN experiments, we’re trying hard to lower the energy of our particles, so that they may be more easily trapped. However, no special treatment here – we get the “standard-issue” CERN building, just like everyone else:

CERN Building 193

The entrance to the Antiproton Decelerator

AD hall

Inside the antiproton decelerator

We live at the Antiproton Decelerator (AD), which takes an injected antiproton beam and reduces the energy by a factor of ~1000, to 5 MeV. The AD is unique; other places in the world produce antiprotons, but CERN is the only place that slows them down to low enough energy for trapping. If we want to make trappable antihydrogen, we had better start with trappable antiprotons!

AD Blackboard

Chalkboard in the AD. Might as well get the Dan Brown references out of the way now...

In the days and weeks ahead I’ll go much more into detail about the experiment – for now, I’ll leave off with a picture of what our experiment looks like, complete with high-precision tape, zip-ties, and aluminum foil:


Experimental apparatus, surrounded by a large magnet and detector systems.